Control device for a gas exchange valve in an internal combustion engine

ABSTRACT

A control device for a gas exchange valve of an internal combustion engine having a multi-membered transmission comprising  
     at least one driving element ( 1 ),  
     actuating elements ( 2 ) each of which actuates one gas exchange valve ( 3) ,  
     a transmission element ( 9 ) which is hinge-connected between the at least one driving element ( 1 ) and an actuating element ( 2 ) which acts on a gas exchange valve ( 3 ),  
     a cam joint ( 15 ) between the transmission elements ( 9 ) and an area of the housing ( 5 ) of the control device, in which a first bearing area which is provided on the transmission element ( 9 ) and a second bearing area which is provided in the housing area are adjustable with respect to one another during operation of the engine,  
     is to be manufacturable easily for extremely accurate operation.  
     To this end, such a control device is characterized in that  
     the second bearing area of the cam joint ( 15 ) forms the radial inside surface of a circular arc-shaped link element which is supported so that it is diplaceable in the direction of the circular arc with a circular cylindrical peripheral surface on the outside radially in a complementary guide surface of the house of the control device.

[0001] This invention relates to a control device for a gas exchange valve in an internal combustion engine according to the preamble of Patent claim 1.

[0002] With such a device known from German Patent DE 38 33 540 C2, the individual adjustable curve joints on the transmission elements are designed so that the curve paths with the help of which an adjustment is possible are designed on the transmission elements. This means that with machining of the transmission elements, which is usually performed separately, and thus applying the curve paths to these transmission elements, inaccuracies in operation by occur in the completely assembled control device due to manufacturing tolerances.

[0003] This invention is concerned with the problem of creating a design of the generic control device in which an extremely high functional precision in operation of the control device can be achieved through simple manufacturing processes that can be handled economically.

[0004] This problem is solved by the design of a generic control device according to the characterizing features of Patent claim 1.

[0005] This invention is based on the general idea of being able to implement the different curve paths within the individual curve joints between the transmission elements and the housing of the control device on a one-piece component if at all possible, while on the other hand supporting this one-piece component displaceably in a stable and accurate manner on a curve path that has been provided and to do so by direct support thereof on a compact area of the housing of the control device.

[0006] Expedient embodiments of this invention are the object of subclaims.

[0007] According to this, adjustment of the curve path of the curve joint, which is supported adjustably in the housing of the control device, can be accomplished by designing the curve path in a link element and adjusting this link element by means of a toothed gear, for example.

[0008] The housing of the control device may advantageously have a circular cylindrical recess in which all the position-determining components of the control device can be aligned on the cylindrical inside circumference of this recess.

[0009] This recess may be situated in particular in an area of the cylinder head of the internal combustion engine.

[0010] Although the peripheral wall of the circular cylinder recess is advantageously designed in one piece for reasons of stability and precision, it is of course also possible to divide the component through the circular cylindrical recess.

[0011] A conventional camshaft, an eccentric drive or a positive control drive with complete forced guidance of the transmission element may be used as the driving elements.

[0012] Advantageous embodiments of this invention are illustrated in the drawing.

[0013] Schematic diagrams in the drawings show the following in the form of a view of a control device mounted in a circular cylindrical recess in a cylinder head:

[0014]FIG. 1 a control device having a conventional camshaft and a gas exchange valve operated by a swiveling lever,

[0015]FIG. 2 a control device according to FIG. 1 in which the camshaft is replaced by an eccentric drive,

[0016]FIG. 3 a control device having a conventional camshaft and cup tappet as the actuating element of a gas exchange valve instead of the swiveling lever according to FIG. 1.

[0017] The control device according to FIG. 1 operates with a conventional camshaft as the driving element and a swiveling lever 2 as the actuating element of a gas exchange valve 3. The entire control device is arranged inside of a circular cylindrical recess 4 in an area of a cylinder head designed in one piece.

[0018] Of the gas exchange valve 3, only the area which is connected directly to the swiveling lever 2 together with a valve spring 6 is shown.

[0019] The camshaft 1, which functions as a driving element is situated on the inside circular lateral cylindrical surface of the recess 4 via a divided bearing block 7.

[0020] A cam 8 driven by the camshaft 1 is connected to a transmission element 9 via a curve joint 10. Within the curve joint 10, a first roll 11, which is rotatably mounted on the transmission element 9, forms the bearing area of this curve joint 10 there. The transmission element 10 is connected via a rotating joint 12 to the swiveling lever 2. On its end, which is at a distance from the valve 3, this swiveling lever 2 is supported pivotably on a supporting element 13. This supporting element 13 is directly supported on the circular cylindrical inside circumference of the recess 4 with this cooperating bearing element 14 and can be combined with and/or interact with such a valve play equalizing device.

[0021] The axis of rotation of the rotating joint 12 of the swiveling lever 2 coincides with the axis of the circular cylindrical recess 4 when the gas exchange valve 3 is closed.

[0022] The transmission element 9 is connected via another curve joint 15 to the housing of the control device, i.e., to the cylinder head 5 here. On this housing and/or the cylinder head 5 on the circular lateral cylindrical surface of the recess 4, a link element 16 is displaceably mounted so that it can be displaced in the peripheral direction of the lateral cylindrical surface of the recess 4 with the curve joint area of the transmission element 9 acting on it.

[0023] The bearing area of the curve joint 15 of the transmission element 9 is designed as a second roll 17, which is rotatably mounted on the transmission element 9, while the bearing area on the link element 16 is designed as a curve path having a particular shape. The particular shape of the curve path consists of the fact that a first area 18 is provided, having a lateral surface which is concentric with the circular cylindrical inside lateral surface of the recess 4 and with a second valve stroke area 19 which is the deciding factor for the stroke of the gas exchange valve 3 being connected to it. The drawing shows the maximum possible displacement positions represented alternatively by a diagram in solid lines for a maximum stroke length of the respective gas exchange valve 3 and in broken lines for a minimum stroke, e.g., a zero stroke. The control device shown in FIG. 1 is intended for an internal combustion engine having multiple cylinders and it has a one-piece link element 16 for this purpose.

[0024] The assignment of the curve path to the first area 18 and the valve stroke 19 to the transmission element 9 is altered by displacement of the link element 16 in the peripheral direction of the lateral cylindrical surface of the recess 4. Therefore, different valve strokes can be adjusted between the two stroke limits described above.

[0025] For displacement of the link element 16 within the recess 4, a toothed gear may be used; in the simplest case, this is a pinion 20, which is rotatably mounted in the cylinder head 5 and engages in a toothed outside area 21 of the link element 16.

[0026] The supporting element 13 for the swiveling lever 2 may be combined and/or equipped with a conventional valve play equalizing device.

[0027] The control device described above functions as described below.

[0028] The camshaft 1 with the cam 8 as the driving element acts via the curve joint 10 on the transmission element 9, which is guided via the other curve joint 15 on the link element 16, which is adjustable within the cylinder head 5 and actuates the gas exchange valve 3 by means of the swiveling lever 2, which is additionally hinge-connected to the transmission element 9. The valve stroke depends on the set position of the link element 16, but a valve stroke can be produced in only one position of the link element 16 in which the curve joint 15 operates effectively within the valve stroke range 19 of the link element 16.

[0029] A spring (not shown) may act on the transmission element 9 for spring-loaded contact of the transmission element 9 with the camshaft 1 and the link element 16.

[0030] It is also conceivable for a slight play to be set through appropriate stops for the transmission element 9 between the basic circular area of the cam 8 of the camshaft 1 and the first roll 11 on the transmission element 9 in order to reduce frictional losses by the system. In this case, a restoring force by means of a spring, for example, is also necessary.

[0031] All the components of the control device which determine position, namely the bearing block 7 of the camshaft 1, the bearing element 14 of the supporting element 13 and the link element 16 with the curve path of the curve joint 15 situated on it are directly aligned with and mounted in the cylindrical inside surface of the recess 4, which is provided in the cylinder head. In particular, the link element 15 is a component which is mounted in an essentially stable and a deformation-free manner in the cylinder head. The area of the cylinder head 5 which is shown as being in one piece may also be designed to be divided for simpler assembly of the control device. It may also be adequate for the recess 4 not to be closed over the entire circumference, i.e., the advantages according to this invention can also be achieved with only a circular cylindrical recess limited to less than 360° of the circumference.

[0032] The embodiment according to FIG. 2 differs from that according to FIG. 1 only in that instead of a conventional camshaft 1 an eccentric drive 22 is used. Therefore, only this component in FIG. 2 is labeled with the respective reference number, while all the other components are free of reference notation like those according to the embodiment in FIG. 1.

[0033] In the embodiment according to FIG. 3, the actuating element for the gas exchange valve 3 is not a swiveling lever 2 but instead is a tappet device 23, which is combined with a valve play equalizing device 24, among other things. The articulated connection of the tappet connecting device 23 to the transmission element 9 is accomplished in an access of rotation which corresponds to that of the swiveling lever 2 in FIG. 1. Inasmuch as no reference numbers are given for the individual components in FIG. 3, they are essentially the same as those given in FIG. 1. 

1. A control device for gas exchange valves (3) of an internal combustion engine having a multi-membered transmission, comprising at least one driving element (1, 22), actuating elements (2, 23) each of which actuates one gas exchange valve (3), transmission element (9) which is hinge-connected between the at least one driving element (1, 22) and an actuating element (2, 23) acting on one gas exchange valve (3) each, a curve joint (15) between the transmission elements (9) and an area of a housing (5) of the control device, in which a first bearing area which is provided on the transmission element (9) and a second bearing area which is provided in the housing area are adjustable with respect to one another during operation of the engine, the second bearing area of the curve joint (15) of the transmission element (9), said bearing area being supported on the housing (5), is designed as an adjustable curve path which influences the path of movement of the transmission element (9) while the first bearing area, which is provided on the transmission element (9) cannot exert any variable movement of the respective transmission element, the second bearing area of the curve joint (15) is formed by the radial inside surface of an arc shaped element (16), the link element (16) is supported so that it is displaceable in the peripheral direction in a complementary guide surface of the housing of the control device, with a circular cylindrical peripheral surface that is on the outside radially, wherein the housing (5) of the control device is provided with a circular cylindrical recess (4), the inside circumference of which at least the driving element (1, 22), a supporting bearing (14) for the actuating elements (2,23) and the link element (16) are supported in a radially defined position.
 2. The control device according to claim 1, wherein for displacement of the link element (16) in the direction of the circular arc, a toothed pinion (20) mounted in the housing (5) cooperates with gear teeth (21) provided in the link element (16).
 3. (canceled)
 4. (canceled)
 5. The control device according to claim 1, wherein only one adjustable link element (16), which is designed in one piece is provided for actuation of a plurality of gas exchange valves (3) which are arranged in a row.
 6. The control device according to claim 1, wherein the housing of the control device is an area of the cylinder head (5) of the combustion engine. 